Web sites of online merchants commonly provide various types of informational services for assisting users in evaluating the merchant' product offerings. Such services can be invaluable to an online customer, particularly if the customer does not have the opportunity to physically inspect the merchant' products or talk to a salesperson.
One type of service involves recommending products to users based on personal preference information. Such preference information may be specified by the user explicitly, such as by filling out an online form, or implicitly, such as by purchasing or rating products. The personalized product recommendations may be communicated to the customer via an email message, a dynamically-generated Web page, or some other communications method.
Two types of algorithmic methods are commonly used to generate the personalized recommendations—collaborative filtering and content-based filtering.
Collaborative filtering methods operate by identifying other users with similar tastes, and then recommending products that were purchased or highly rated by such similar users. Content-based filtering methods operate by processing product-related content, such as product descriptions stored in a database, to identify products similar to those purchased or highly rated by the user. Both types of methods can be combined within a single system.
Web sites also commonly implement services for collecting and posting subjective and objective information about the product tastes of the online community. For example, the Web site of Amazon.com, the assignee of the present application, provides a service for allowing users to submit ratings (on a scale of 1-5) and textual reviews of individual book, music and video titles. When a user selects a title for viewing, the user is presented with a product detail page that includes the title's average rating and samples of the submitted reviews. Users of the site can also access lists of the bestselling titles within particular product categories, such as “mystery titles” or “jazz CDs.”